1. Field
The present invention relates to the manufacture of composite structures and, more specifically, to an apparatus and associated method for laying or disposing elongate tapes in a contoured configuration to form the composite structures.
2. Background
Insert Composite members are typically formed of a reinforcement material that is disposed in a matrix material. For example, the reinforcement material can be a fibrous material such as graphite, and the matrix material can be a resinous polymer material. According to one conventional manufacturing method, the composite material is disposed in the desired shape of the composite member by laying a plurality of elongate composite tapes to progressively build the layers of the member. An automated operation for forming the composite member can begin by using a contoured tape laying machine (CTLM) to dispose a first layer of tapes onto a mandrel that defines the shape of the composite member. The CTLM includes a roll or other supply of the tape, which is dispensed onto the mandrel with a tape placement head that guides the tapes onto the mandrel in the desired configuration. That is, the tape placement head provides relative movement between the mandrel and the head so that the head moves over the surface of the mandrel. The head usually makes repeated passes over the mandrel in a defined pattern until the mandrel is entirely covered, and additional layers of the tape are built up by continued passes of the head over the surface. A compaction roller presses the tape against the mandrel or the previously disposed layers of tape to facilitate adhesion of the multiple layers of the tape.
This conventional CTLM can accurately place the tapes, and the automated process can increase the speed at which the composite members can be formed. In addition, the CTLM is typically able to lay the tapes in a variety of configurations corresponding to the surface of a select mandrel to thereby form the composite member to the desired shape. In one conventional method for manufacturing a complex contoured surface, a first tape is disposed across the mandrel along a natural path, i.e., a course along which the tape can be disposed substantially flat against the mandrel with minimal stressing or wrinkling of the tape. For a contoured mandrel, the natural path is typically curved. After the first tape is disposed along a natural path, subsequent tapes are disposed along natural paths that extend across the mandrel in a similar direction as the first tape, i.e., generally parallel to the first tape. However, due to the complex contour of the mandrel, the natural paths of the adjacent tapes are not parallel along their entire lengths. Typically, the tapes are disposed about as close as possible while avoiding any overlapping of adjacent tapes (i.e., “laps”), since overlapping of tapes can decrease the strength of the resulting composite member. Thus, the edges of adjacent tapes that are disposed along natural paths define spaces or “gaps” therebetween, and the size of the gaps can vary along the lengths of the tapes. The gaps can also decrease the strength of the resulting composite member. In some cases, the resulting decrease in strength due to the laps and/or gaps may be sufficiently high as to preclude the use of the CTLM for forming the member.
Therefore, there exists a need for an apparatus and method for disposing tapes to define complex configurations while reducing or minimizing the laps and/or gaps defined by adjacent tapes and for doing so without substantially wrinkling the disposed tapes.